1. Field of the Invention
This invention relates generally to voice calls being digitized and carried over digital communications networks, and more particularly to the adaptation of a public switched telephone network (PSTN) intelligent call routing engine as a call routing engine for voice-over-IP (VoIP) environment calls.
2. Background Information
Many systems are known and deployed for managing voice calls through the public switched telephone network or through private branch exchanges (PBXs) or other such private communications networks. These known systems include automatic call distribution systems (ACD's) that provide real-time premise switching and directing or other such call management and reporting capabilities. For example, the status (busy, or not) of human agents charged with answering an incoming call can be maintained by such a system, with new incoming calls directed to an available agent. Such agent state information, when accumulated in real-time across geographically dispersed call center ACD'S, forms a primary routing criterion for current intelligent call routing engines. Parameters of the incoming call, for example the calling line ID and/or network prompted caller entered digits, may likewise be used by the routing engine as decision factors in determining optimal agent and/or peripheral device (e.g. voice response unit, etc.) routing. The time, duration, statistics, and disposition of the call may be recorded as data for future use. Priority and other such criteria can be generated and stored for more efficient handling of incoming calls. For example, routing of calls is routinely accomplished wherein calls can be successively transferred and/or be part of a conference call using tie lines back through the public switched telephone network. The capabilities of such intelligent call routing engines are now well-known in the art.
With its origins in the DOD ARPAnet of the late sixties, the Internet has matured into a matrix of interconnected computers around the world—spanning educational, commercial, government, and private institutions. Based on the well-known Transmission Control Protocol/Internet Protocol (TCP/IP) protocol suite, Internet features have developed over time to facilitate a wide range of local and wide area network protocols and accompanying applications, e.g. file transfer protocols (FTP), world wide web (HTTP, HTML), news readers (USENET, NNTP), and email (SMTP). The ubiquitous layered protocol models (e.g., the five layer Internet Reference model and the seven layer International Organization for Standardization—OSI) are widely known, and systems have been implemented at virtually all “stack” layers to render information transfer using the IP protocol suite as simple, accessible, and direct—thus facilitating the Internet's phenomenal growth.
Despite the maturity of an entire suite of Internet protocols (or, in part, because of it) researchers continue to seek out additional useful applications of the technology. One such relatively new application has been with the encoding of voice telephone communication to allow transmission over the Internet. The technology functions by breaking analog voice signals into digitized “packets,” which in turn are transmitted using Internet protocols (e.g. UDP—User Datagram Protocol). Relative to the maturity of the PSTN telephone infrastructure, technology for the manipulation of voice call establishment and the transmission of voice messages over IP is relatively new and immature. VoIP does, however, hold a number of advantages for carrying voice over the legacy (the existing known) PSTN network, both economic and technological.
U.S. Pat. No. 6,141,341, by Jones et al. and assigned to Motorola describes a VoIP system. This patent discloses the dual use of a telephone. The telephone is connected to public switched telephone network (PSTN) and can send and receive regular voice messages via the PSTN. A signal or other mechanism is disclosed that allows the system to conduct an IP based call (VoIP). When a VoIP call is detected the system operates over the Internet to complete the voice message call. The components of a VoIP system, as in this patent, are shown in FIG. 1. Here telephones 2 are connected via some type of fan out box 4, known in the art, to a gateway (GW) 6. The GW connects to the public switched telephone network 8 via a network interface unit (NIU) 10. The GW also connects to an Internet Access device 12 (e.g. a cable modem) that in turn connects to the Internet or other such wide area network 14. There may be some form of voice messaging system as known in the art connected to the telephone network 2, but the full performance of mature call routing systems and the flexibility of the Internet are both largely unfulfilled.
The International Telecommunications Union standard gatekeeper logic embodied in its H.225 standard, referenced below, defines, perhaps, the most relevant prior art to while still falling short of the performance provided by the present invention.
The evolution of VoIP technology continues, and to date the commercial success of VoIP based systems has been moderate but measured. One key reason for the lack of more profound success with VoIP thus far is the requirement for transitional technologies to bridge the gap between PSTN and VoIP, allowing—for example—commercial service provider customers to exploit their significant investment in older switching technology and legacy telephone systems while migrating to a packet-based backbone digital medium. Often, this hybrid, transitional mode dictates a need for dual or composite systems, where the advantages of each are not fully realized, and the combination suffers from cumbersome artificial compromises.
A second (but equally profound) reason that VoIP deployment has not accelerated more swiftly is that the technology specific to feature-rich call routing and control in a VoIP environment is in its infancy relative to the longstanding analogous PSTN capabilities.
The present invention is directed to marrying the flexible and mature intelligent voice call management features of PSTN call routing systems with the analogous (albeit not yet mature) call address resolution mechanism of the newly evolving technology to facilitate voice calls over a digital communications network (VoIP). The invention offers a number of distinct advantages over current VoIP call addressing mechanisms, including the ability to exploit the fully mature, proven, and enriched features of the PSTN routing engine to provide features not yet available in known VoIP systems. A secondary appeal of the invention is its inherent advantage (to both commercial PSTN service providers as well as enterprise/internet users) migrating their voice communication to VoIP technologies from existing PSTN facilities deploying such a PSTN call routing engine. In such an environment the call routing engine may perform both PSTN and VoIP duties concurrently, easing the transitional burden of redundant configuration and switchover.
The invention presented herein provides an approach to exploit existing, technologically superior PSTN SCP level toll-free intelligent routing capabilities in an application that benefits, immediately, VoIP.